All I can add is that I eventually plan to do a single-track "spacer" module in HO, and mine will depict a city street running scene, with lots of buildings made from DPM packs (some semi-flat), and probably a grade crossing. An expanded version of Andy Gautrey's Grunge Street. http://www.rmweb.co.uk/community/index. ... -crossing/

But then, yours will be a lot longer than mine. On that length, perhaps I'd go for a "less is more" concept, and just have the whole lot as sandy scrub, for the pleasure of just running a train through it.

6m in N scale is similar to 12m (40ft +) in HO , while a single track with just scenery sounds tempting, a few items for scenic interest could be included. Culverts, a bridge, an abandoned spur , some slight hill sides , trees and brushes , a grade crossing or overpass along the way etc. it would keep the viewers interest longer than a salt flat for example ...